This invention relates generally to an electric connection box for automotive wiring and more particularly to such an electric connection box of the type in which bus bars constituting internal circuitry can be easily arranged and mounted in position.
Generally, as shown in FIG. 9, the internal circuitry of a conventional electric connection box is constituted by bus bars which are stamped from a metal sheet and have their end portions and/or intermediate portions thereof bent into upstanding tabs serving as terminals for external connection. However, as shown in FIG. 10, when providing two juxtaposed tabs 2A and 2A on a bus bar 1A interposed between two bus bars 1B and 1C, it is necessary to provide respective roundabout portions 1B' and 1C' in the adjacent bus bars in order to accommodate the portions 2A', which are the tabs 2A prior to bending. This lowers the yield of the stamping operation and the density of the mounting of the bus bars, and also makes the circuitry complicated.
To overcome this difficulty, there has been proposed an electric connection box as shown in FIG. 11. More specifically, a plurality of parallel bus bars 4 are mounted along respective edges thereof on a lower case 3; the lower case 3 also serving as an insulating plate. Branch bus bars 5 are mounted on the bus bars 4. A body 5a of each branch bus bar 5 is bent at one end 5b into an L-shape, and the other end portion 5c serves as a contact portion for connection to an external circuit. The L-shaped portion 5b of each branch bar 5 is fixedly secured to a respective one of the bus bars 4 by welding, such as spot welding, and then an upper case 6 is connected to the lower case 3, so that the contact portions 5c are received in position in various insulating housings, such as a connector housing 7a, a fuse cavity 7b and a relay cavity 7c, provided on the upper case 6.
Since the bus bars 4 and the branch bus bars 5 are fixedly connected together by welding, it is rather difficult to accurately position the contact portions 5c relative to one another and also relative to the above insulative housings. Particularly, when a plurality of branch bars 5 are fixedly connected to one bus bar 4, the overall shape of such bus bar arrangement becomes complicated, and if the order of the assemblage is wrong, the assemblage must be redone. This leads to low productivity.